1. Field of the Invention
This invention relates generally to tape cassettes of the type in which a supply of tape is contained in a housing for protecting the tape when the cassette is not in use, and more particularly is directed to improvements in tape cassettes of the described character for ensuring the proper positioning of the tape cassette in respect to a cassette holder or loading mechanism by which the cassette is positioned on a magnetic recording and/or reproducing apparatus.
2. Description of the Prior Art
The use of tape cassettes in magnetic recording and/or reproducing apparatus has been expanding steadily as a result of the protection afforded to the tape when the cassette is not in use and the ease with which the tape can be loaded on the apparatus for a recording or reproducing operation. Initially, tape cassettes were used in connection with magnetic recording and/or reproducing apparatus of the type having a fixed magnetic head or heads projected into the cassette housing through a relatively small window or windows in the latter for engaging the tape within the cassette housing during a recording or reproducing operation. However, more recently it has been proposed to employ tape cassettes in magnetic recording and/or reproducing apparatus of the type having one or more rotary magnetic heads, for example, as in apparatus for recording and/or reproducing video signals on a magnetic tape. In the last mentioned use of tape cassettes, it is necessary that the tape cassette be easily and accurately positioned on the apparatus in order to ensure the reliable operation of an associated tape loading device by which the tape is withdrawn from the cassette housing and wrapped about a cylindrical guide drum for scanning in oblique tracks by the rotary magnetic head or heads associated with such drum.
When the recording and reproducing of signals on the tape is effected by a rotary magnetic head or heads, as above, it is necessary to provide the cassette housing with an opening through which the tape can be withdrawn from the housing for engagement with such head or heads associated with the drum by means of the tape loading device. In an existing tape cassette of the foregoing type, for example, as disclosed in U.S. Pat. No. 3,735,939, issued May 29, 1973, and having a common assignee herewith, the cassette is provided with a lid which is normally spring biased to cover the tape extending across the opening of the cassette housing when the cassette is not in use, and which is movable to an opened position exposing the tape at the opening of the cassette housing when the cassette is disposed in an operative position on the magnetic recording and/or reproducing apparatus. U.S. Pat. No. 2,941,741 similarly discloses a tape cassette in which an opening extends along the entire length of one side of the cassette housing and a lid is provided for normally covering such opening.
In magnetic tape recording and/or reproducing apparatus having a rotary magnetic head or heads, as described above, there is usually provided a cassette loading mechanism having a holder which is adapted to receive the cassette in a conveniently elevated position and which is then movable downwardly for disposing the cassette in an operative position at which the lid of the cassette housing is opened and the tape loading mechanism of the apparatus is engageable with the tape extending across the exposed opening of the cassette housing. Usually, the holder of the cassette loading mechanism is adapted to have the cassette slidably inserted therein either in the direction parallel to the side of the cassette housing provided with the opening or in the direction perpendicular to that side of the cassette housing. Whether the cassette is slidably insertable into the holder in one or the other of the foregoing directions, it will be apparent that such insertion of the cassette must be effected with the cassette housing in only a single orientation relative to the holder if the cassette is to be properly disposed for engagement of the tape loading mechanism with the tape extending across the opening of the cassette housing when the cassette is moved to its operative position by the cassette loading mechanism. However, existing tape cassettes and the corresponding holders for receiving the same do not prevent insertion of the cassette into the holder except in a single predetermined relative orientation, that is, the cassette may be inserted in either an upside down or front to rear position in respect to its desired orientation relative to the cassette holder.